Method

Peel off the strings from the celery stalks, then cut the stalks into batons about 5cm long and 5mm–1cm thick. Heat the butter and oil in a pan, add the celery, season well and stir. Cover tightly and cook over a low heat for 15 minutes, stirring occasionally until the celery is soft. Sprinkle with the parsley.

Meanwhile, remove the crusts from the bread and soak it in water. Squeeze out the excess water and blitz the bread in a food processor with the other sauce ingredients until smooth. Serve the celery with the sauce.